Going Up? Private Group Begins Work on Space Elevator

Space.com ^ | 8/19/02 | Leonard David

[Brett66]

Similar article posted here:

Going up? Space elevator wins support U.S. company builds on Russian idea

This one was more interesting though.

[Brett66]

indexed

[Skibane]

The first space elevator could possibly be constructed at a price tag of between $7 billion to $10 billion

Sounds relatively cheap, as major space programs go. Anybody happen to know what the GPS project cost?

The military implications would be enormous — which probably means they could get the government funding to make it happen.

[Consort]

..Yeh, I'm Otis...but we don't need no elevators in Mayberry.

[John Jamieson]

Sorry guys, this can't get around physics. Same increase in energy required per pound as always. Just a neat wire to follow up.

EXNASA

It would be a better investment to buy Enron, NewPower and Worldcom.

[NonZeroSum]

There are a lot of problems with this concept, but the energy per pound is not one of them. That's just a few bucks.

[Bogey78O]

But the cost of deriving energy via chemical reaction is quite high. The cost of electricity derived from nuclear power is quite less.

[Bogey78O]

But the cost of deriving energy via chemical reaction is quite high. The cost of electricity derived from nuclear power is quite less.

[John Jamieson]

It's not the cost of the energy, it the cost of turning the energy into altitude and velocity that hurts. The Space Shuttle's actual fuel cost is well below 1% of the total launch cost.

[John Jamieson]

Same answer as above.

I like nuke power by the way, it's the only long term solution this country has.

[NonZeroSum]

But the point of the space elevator is that it reduces the cost of transportation to a little above the basic energy costs, so I don't understand your original comment.

[John Jamieson]

Just HOW does it do that?

You can't just pullup a payload without throwing yourself out of obit. The payload has to be boosted up the line, same as it would be without the line.

Now if you happen to have an infinite supply of mass already at the top end, you can send down the same amount as your pulling up and remain stable.

There ain't no free lunch (or launch, either).

[Swordmaker]

What? No environmental impact study for the geosynchronous orbit?? How about the stratosphere? Anchor point?

The nuisance lawsuits alone will take a couple of centuries to litigate.

[John Locke]

You're right. The energy required to accelerate one kg to escape velocity is approximately 18 kilowatt-hours. For that much electricity, you'd typically pay about two dollars (well, maybe 20 in California).

Chemical rockets are very, very inefficient.

[John Locke]

Not a hard problem. You have to conserve not mass but angular momentum. So you can balance a lot of payload merely by moving a counterweight outwards along the tether.

When you run out of tether, drop mass back to Earth and you can reset the counterweight.

So, we need a regular supply of mass at the top of the tether. Fire it off the Moon with a magnetic railgun, again at very low cost (about 15 cents per kg in raw energy - yes, energetically high Earth orbit is much, much closer to the Moon).

[lotus]

I think it's a scam like the free energy thing. When a spinning skater throws their arms back out they slow their spin....conservation of energy

Personaly I think the twine will wrap around and around.

[Swordmaker]

Sorry guys, this can't get around physics. Same increase in energy required per pound as always. Just a neat wire to follow up.

John, you are right... and you are wrong.

While the energy accumulated in the object lifted to orbit will be the same, the amount of energy expended per DELIVERED pound will NOT be the same. Since the MODE of lift is not self-contained, it is unnecessary to lift fuel, tanks, guidance, etc. along with payload. Lifting 10,000 lbs to geosynch orbit would no longer require lifting 1,000,000 lbs of vehicle and fuel off the ground and throwing 99% of it away in the process. Nor would great speeds like 25,000 MPH escape velocity be required. Reusable 'cars' with no internal fuel or energy supplies would do the job climbing the cable at 10 - 1000 mph.

Using a "space elevator", electrical power could be supplied to a "car" which would use electric motors and gripping mechanisms to 'climb' the 'tower'. Much of this power could be reclaimed when the "car" descended by using electomagnetic braking to retard the fall down the 'tower'... for greater efficiency, make it a double track system and have a descending car come down while an ascending car is raised to minimize power draw from the grid.

Most designs I have seen would incorporate a "counter weight" extended beyond the geosynch point and use 'centripetal force' to provide stability and offset the effects of added weight of cars and opposite reaction forces imparted by the cars 'climbing' the cable. Several different modes have been suggested for fine tuning this counterbalance as cars are added, climb and descend. Once the materials are created, the rest is merely engineering... and legal entanglements.

Power the system with solar power antenna arrays at the space side geosynch 'anchor' and I bet it could be a net profit center... supplying earthside power TO the grid.

The technology and design exist... the only things really holding back such a construction are economics and the 'unobtainium' material to make the cable (it has to withstand its own weight, the counterbalance force, support the weight of electrical cabling... AND the weight of cars and freight as well as the forces moving them... and withstand the varied environments.

I doubt the carbon tubes described in the article are up to the task... 100 times stronger than steel is probably not strong enough. 1000 times might be.

[NonZeroSum]

Actually, the biggest problem with it is that once it's up, you can't have anything else in a low earth orbit (or any orbit below the top of the tether, well beyond GEO, other than geosynchronous) because it will eventually collide with it.

[John Jamieson]

I think you left the half out of the equation. I get about half as much. You would also have to add in the potential energy increase. How do you lift the string and counterweight in the first place? Why would you even need a string and counter weight?

Sounds like you want an electric space vehicle with a very long extention cord. Go for it. The rest of us are still stuck on planet earth.

[RightWhale]

Otis Elevator said last year they were interested in this.